When you are provider services specific to an event that you don't get to set the date, things can get messy.
Weddings, parties, corporate, anyone?
For anyone that helps get the party started, I've got my all time favorite rescheduling clause that makes sure you dont get stuck hanging onto a perpetually postponed event for your prices years ago. 
It makes sure your time and the fact that you didnt book clients for that event date is paid for and respected! 

Grab it now!